Electro-luminescence display device and driving apparatus thereof

Abstract

The present invention relates to an electro-luminescence display and a driving method thereof wherein a thin film transistor is prevented from the deterioration, to thereby improve a picture quality. An electro-luminescence (EL) display, including: a plurality of drive voltage supply lines; N compensation voltage supply lines; EL cells at each crossing of a plurality of data lines and a plurality of gate lines in a matrix, wherein the EL cells emit light in response to currents applied from the drive voltage supply lines; driving thin film transistors (TFT) connected between the EL cells and compensation voltage supply lines that control the current applied to the EL cells; and a bias switch, connected between the N−1th compensation voltage supply line and a control terminal of the driving TFT connected to the Nth compensation voltage supply line that applies a bias voltage to the driving TFT when a scan pulse is supplied to the N−1th gate line.

1. An electro-luminescence display, comprising:
 a plurality of drive voltage supply lines; 
 a plurality of compensation voltage supply lines; 
 EL cells at each crossing of a plurality of data lines and a plurality of gate lines in a matrix, wherein the EL cells emit light in response to currents applied from the drive voltage supply lines; 
 driving thin film transistors (TFTs) connected between the EL cells and compensation voltage supply lines that control the current applied to the EL cells; and 
 a bias switch, connected between a N−1th compensation voltage supply line of the plurality of compensation voltage supply lines and a control terminal of a Nth driving TFT connected to a Nth compensation voltage supply line of the plurality of compensation voltage supply lines to apply a negative bias voltage to the Nth driving TFT connected to the Nth compensation voltage supply line, thereby compensating for a change of threshold voltage of the Nth driving TFT when a scan pulse is supplied to a N−1th gate line of the plurality of gate lines, wherein the bias switch is controlled by the scan pulse supplied to the N−1th gate line, and 
 wherein the bias switch includes: 
 a control terminal connected to the N−1th gate line; 
 a first input terminal connected to the N−1th compensation voltage supply line; and 
 a second input terminal connected to the control terminal of the Nth driving TFT that is connected to the Nth compensation voltage supply line. 
 
     
     
       2. The EL display of  claim 1 , further comprising:
 a switching thin film transistor, connected to the gate line, the data line and the control terminal of the driving TFT; and 
 a storage capacitor connected between the compensation voltage supply line and the control terminal of the driving TFT. 
 
     
     
       3. The EL display of  claim 2 , further comprising:
 a compensation voltage generator that generates a compensation voltage with a high state; and 
 a shift register that sequentially shifts the compensation voltage with a high state to supply the compensation voltage to the plurality of compensation voltage supply lines. 
 
     
     
       4. The EL display of  claim 3 , wherein when the scan pulse is supplied to the N−1th gate line, the compensation voltage with a high state from the shift register is supplied to the Nth compensation voltage supply line and the compensation voltage with a low state from the shift register is supplied to the N−1th compensation voltage supply line. 
     
     
       5. The EL display of  claim 4 , wherein when the scan pulse is supplied to the N−1th gate line, the control terminal of the driving TFT is supplied with data via the switching TFT and the second input terminal is supplied with a compensation voltage with a low state from the N−1th compensation voltage supply line. 
     
     
       6. The EL display of  claim 4 , wherein when the scan pulse is supplied to the N−1th gate line, the bias switch supplies a compensation voltage with low state from the N−1th compensation voltage supply line to the control terminal of the driving TFT connected to the Nth compensation voltage supply line and a compensation voltage of high state is supplied from the Nth compensation voltage supply line to the second input terminal of the driving TFT.